Hydrocarbon drag reduction with interpolymer complexes containing novel sulfo-octene

ABSTRACT

A method for reducing the frictional drag of an organic liquid in flow through pipes or conduits having a continuous bore therethrough which comprises adding about 0.001 to about 0.5 grams of a polymeric complex to 100 ml of said organic liquid, wherein the polymeric complex is the reaction product of a metal neutralized sulfonated octene-1/ethylene/ethylidene norborene terpolymer and a basic nitrogen-containing copolymer, said basic nitrogen containing copolymer being a copolymer of vinylpyridine with another monomer selected from the group consisting of styrene, t-butyl styrene, alkylacrylate, alkylmethacrylate, butadiene, isoprene, vinyl chloride and acrylonitrile.

FIELD OF THE INVENTION

To flow liquids in pipes energy must be expended to overcome frictionallosses. This energy is extracted from the liquid pressure, whichdecreases along the pipe in the direction of flow. For a fixed pipediameter these pressure drops increase with increasing flow rate. Whenflow in the pipe is turbulent (flow Reynolds number which equals meanfluid velocity times pipe diameter divided by fluid kinematic viscositygreater than about 2,000) the relationship between pressure drop andflow rate can be altered by the addition of small amounts of certainhigh molecular weight polymers to the liquid. These polymers interactwith the turbulent flow processes and reduce frictional pressure lossessuch that the pressure drop for a given flow rate is less, or the flowrate for a given pressure drop is larger. This phenomenon is commonlycalled drag reduction. It has been used in commercial oil pipelines,fire hoses and storm sewers to increase the flow capacities of existingsystems. It can also be used to reduce supply pressures, pumping costs,and/or pipe diameters for given flow capacities.

BACKGROUND OF THE INVENTION

High molecular weight hydrocarbon soluble polymers, such aspolyisobutylene, polystyrene and several alpha olefins, have beendemonstrated to reduce drag in turbulent flows of hydrocarbon liquids.Generally, the drag reduction effectiveness of these polymers improveswith increasing molecular weight; however, the tendency for the polymersto permanently degrade via molecular scission in local extensional flowswithin pumps or turbulent pipeflows also increases with increasingpolymer molecular weight. This invention discloses efficient dragreduction in organic liquids resulting from a novel class ofinterpolymer complexes containing sulfonated copolymers of alphaolefins.

It is well known that alpha olefins can be polymerized in the presenceof coordination catalysts (Ziegler-Natta). These catalysts generallyconsist of materials such as transition metal halides (e.g., TiCl₃) andorganometallic cocatalysts (e.g., R₃ Al or R₂ AlCl). Most of the effortsin this field have centered on maximizing catalyst activity and polymerstereoregularity/crystallinity (e.g., U.S. Pat. Nos. 3,116,274,3,476,730, 3,156,681 and 4,240,982). Items of commerce in this categoryare isotactic polypropylene and poly(1-butene). These stereoregular,crystalline polymers have excellent physical and mechanical propertiesand are well suited to forming molded objects, such as pipe or tubing,which require rigidity. However, these materials have limited use aspolymer additives to hydrocarbon solutions (e.g., viscosifiers, dragreducers, antimisting agents).

A smaller body of knowledge exists on the preparation of ultra-highmolecular weight noncrystalline alpha olefins suitable for use ashydrocarbon viscosifiers, drag reducing agents or antimisting additives,etc. Examples of such art are found in U.S. Pat. Nos. 4,289,679,4,358,572, 4,371,455 and British Pat. No. GR 2074,175A. Thenoncrystalline nature of these polymers makes them amenable to easydissolution in organic media. However, these materials are completelynonfunctional and their solution properties can be optimized only byadjustment of polymer molecular weight (+ distribution). In other words,there are no reactive groups on these chains suitable for modificationor interaction.

Reports of functional alpha olefins in Ziegler-Natta polymerizations aresparse. A notable exception is the copolymerization of propylene withthe methyl ester of undecanoic acid (Japanese Patent Application Nos.57-152767, 57-188996, 57-188997). However, the product of this reactionis characterized by very low levels (0.1-0.3 mole percent) of functionalgroup incorporation. Also, this polymer product is highly crystallineand, thus, not useful as hydrocarbon viscosifiers, drag reducing agentsor antimisting additives.

The instant invention is distinguished from the functional/short chainalpha olefin art (Japanese Patent Application Nos. 57-152767, 57-188996,57-188997) by the lower levels of crystallinity. Thus, the instantcomposition is useful for hydrocarbon solution applications, e.g., dragreduction, viscosification, antimisting additives, etc., whereas thecrystalline polymers of prior art are not. In the instant inventionfunctionalization of a copolymer of octene-1 is achieved by sulfonation,which in turn enables association of shorter molecular weight chainsinto a larger system effective for drag reduction. The sulfonationrequires a copolymerization with a monomer resulting in a double bond inor pendent to the polymeric chain.

In U.S. Pat. No. 4,508,128 complexes of Zn-S-EPDM/styrene vinylpyridineare described. The complexes of the instant invention are more solublein organic liquids, such as crude oil, than those described in U.S. Pat.No. 4,508,128 as a result of the inherently lower levels ofcrystallinity obtained with 1-octene rather than ethylene/propylene (EP)polymers. This enhanced solubility is most pronounced for very highmolecular weight (>1,000,000) polymers and generally improves polymerdrag reduction activity.

The present invention discloses drag reduction agents for organicliquids which are polymer complexes of a copolymer of polystyrenevinylpyridine complexed with a zinc salt of a sulfonated1-octene/ethylene/ethylidene norborene terpolymer.

SUMMARY OF THE INVENTION

The present invention relates to unique and novel drag reduction agentsfor organic liquids which are organic solutions of water insolublepolymer complexes of a copolymer of polystyrene vinylpyridine complexedwith a zinc salt of a sulfonated octene/ethylene/ethylidene norboreneterpolymer. The necessary concentration range of the polymer complex inthe hydrocarbon liquid in order to have an effective drag reductionagent is about 0.001 to about 1.00 grams polymer complex per 100 ml oforganic liquid.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to unique and novel drag reduction agentsfor hydrocarbon liquids which are hydrocarbon solutions of waterinsoluble polymer complexes of a copolymer of polystyrene vinylpyridinecomplexed with a zinc salt of a sulfonated 1-octene/ethylene/ethylidenenorborene terpolymer. The necessary concentration range of the polymercomplex in the hydrocarbon liquid in order to have an effective dragreduction agent is about 0.001 to about 1.00 grams polymer complex per100 ml of hydrocarbon liquid.

The salt of the octene-1/ethylene/ENB terpolymer has the formula:##STR1## wherein x is about 40 to about 98 mole percent, more preferablyabout 45 to about 90, and most preferably about 50 to about 80; y isabout 1 to about 60 mole percent, more preferably about 2 to about 50and most preferably about 3 to about 40; the balance between 100% andthe the combined x and y is the mole percent ENB; Z represents the molepercent of sulfonated species attached to ENB where z is about 0.1 toabout 10 mole percent, more preferably about 0.1 to about 8.0 molepercent and most preferably about 2 to about 6; and M⁺ represents atransition metal ion. The balance of such an ion can be greater than one(e.g., zinc) in which case one ion can neutralize more than onesulfonate group or can be attached to another group (such as acetate).The number average molecular weight of the sulfonated terpolymer asmeasured by GPC is about 10,000 to about 20,000,000, more preferably50,000 to about 15,000,000 and most preferably about 100,000 to10,000,000.

The process for preparing the sulfonated polymer comprises the steps ofterpolymerization of octene-1/ethylene, and ethylidene norborene with aVCl₄ and ethylene-sesquichloride catalyst in an alkane solvent at atemperature of about 0° C. to about 60° C. for about 3 minutes to about4 hours under an inert atmosphere to form the terpolymer ofoctene-1/ethylene/ethylidene norborene. The terpolymer is recovered fromsolution by precipitation with an antisolvent and purified byredissolving in an alkane solvent with an antisolvent.

In carrying out the process to form the sulfonated polymer theterpolymer of octene-1/ethylene/ethylidene norborene, the terpolymer isdissolved in a non-reactive solvent, such as a chlorinated aliphaticsolvent, chlorinated aromatic hydrocarbon, an aromatic hydrocarbon or analiphatic hydrocarbon, such as carbon tetrachloride, dichloroethane,chlorobenzene, benzene, toluene, xylene, cyclohexane, pentane,isopentane, hexane, isohexane or heptane. The preferred solvents are thelower boiling aliphatic hydrocarbons. A sulfonating agent is added tothe solution of the elastomeric polymer and non-reactive solvent at atemperature of about -100° C. to about 100° C. for a period of time ofabout 1 to about 60 minutes, most preferably at room temperature, forabout 5 to about 45 minutes and most preferably about 15 to about 30.Typical sulfonating agents are described in U.S. Pat. Nos. 3,642,728 and3,836,511, previously incorporated herein by reference. Thesesulfonating agents are selected from an acryl sulfate, a mixture ofsulfuric acid and an acid anhydride or a complex of a sulfur trioxidedonor and a Lewis base containing oxygen, sulfur, or phosphorus. Typicalsulfur trioxide donors are SO₃, chlorosulfonic acid, fluorosulfonicacid, sulfuric acid, oleum, etc. Typical Lewis bases are dioxane,tetrahydrofuran, tetrahydrothiophene or triethylphosphate. The mostpreferred sulfonation agent for this invention is an acyl sulfateselected from the group consisting of benzoyl, acetyl, propionyl andbutyryl sulfate. The acyl sulfate can be formed in situ in the reactionmedium or pregenerated before its addition to the reaction medium in achlorinated aliphatic or aromatic hydrocarbon.

It should be pointed out that neither the sulfonating agent nor themanner of sulfonation is critical, provided that the sulfonating methoddoes not degrade the polymer backbone. The reaction is quenched with analiphatic alcohol, such as methanol, ethanol or isopropanol, with anaromatic hydroxyl compound, such as phenol, a cycloaliphatic alcohol,such as cyclohexanol, or with water. The acid form of the sulfonatedelastomeric polymer has about 4 to about 200 meq. SO₃ H groups per 100grams of sulfonated polymer, more preferably about 10 to about 100; andmost preferably about 10 to about 50. The meq. of SO₃ H grams of polymeris determined by both titration of the polymeric sulfonic acid andDietert Sulfur analysis. In the titration of the sulfonic acid thepolymer is dissolved in solvent consisting of 95 parts of toluene and 5parts of methanol at a concentration level of 50 grams per liter ofsolvent. The acid form is titrated with ethanolic sodium hydroxide to anAlizarin-Thymolphthalein end point.

The acid form of the sulfonated terpolymer is gel-free andhydrolytically stable. Gel is measured by stirring a given weight ofpolymer in a solvent comprises of 95 toluene-5-methanol at aconcentration of 5 weight percent for 24 hours, allowing the mixture tosettle, withdrawing a weighted sample of the supernatant solution andevaporating to dryness.

Hydrolytically stable means that the acid function, in this case thesulfonic acid, will not be eliminated under neutral or slightly basicconditions to a neutral moiety which is incapable of being converted tohighly ionic functionality.

Neutralization of the acid form of the sulfonated terpolymer is done bythe addition of a solution of a basic salt to the acid form of thesulfonated elastomeric polymer dissolved in the mixture of the aliphaticalcohol and nonreactive solvent. The basic salt is dissolved in a binarysolvent system consisting of water and/or an aliphatic alcohol. Thecounterion of the basic salt can be selected from antimony, iron,aluminum, lead or Groups IA, IIA, IB or IIB of the Periodic Table ofElements and mixtures thereof. For the purpose of this inventionpreferred counterions are from the group of transition elements asdescribed below. The anion of the basic salt is selected from acarboxylic acid having from about 1 to about 4 carbon atoms, a hydroxideor alkoxide and mixtures thereof. The preferred neutralizing agent is ametal acetate, more preferably zinc acetate. Sufficient metal salt ofthe carboxylic acid is added to the solution of the acid form of theelastomeric polymer to effect neutralization. It is preferable toneutralize at least 95% of the acid groups, more preferably about 98%,most preferably 100%.

We have surprisingly found that a very important factor in determiningthe strength of the interaction between the amine-containing polymer andthe sulfonated terpolymer is the nature of the counterion. There are,broadly speaking, three major classes of such counterions. The firstclass, which are less preferred, are those metals of Group I and GroupIIA, which include Li, Na, K, etc., Be, Mg, Ca, etc. We have found thatthese species do not interact as strongly with amine groups as the morepreferred species described below. Those metals are commonly defined asmembers of the transition elements (see chemical text: ChemicalPrinciples and Properties, by M. J. Sienko and R. A. Plane, McGraw HillBook Company, 1974, page 19). These metal cations are best exemplifiedby zinc and interact strongly with pyridine and similar amines. As aconsequence, a zinc neutralized sulfonated terpolymer interacts muchmore strongly with a styrene/vinyl pyridine copolymer than does amagnesium or sodium neutralized system. It is for this reason that thetransition elements are preferred, with zinc, copper, iron, nickel andcobalt being especially preferred. We also include antimony and lead assuitable cations. Other suitable counterions are titanium, vanadium,chromium and manganese.

A third species is the free acid of the sulfonated terpolymer, whichwill also interact with amine-containing polymers. In this latter case,it is clear that the interaction is a classic acid-base interaction,while with the transition metals a true coordination complex is created,which is due to the donation of the electron pair of the nitrogenelement. This distinction is a very important one and sets thesecomplexes apart from classic acid-base interactions. The surprisingobservation is that such coordination complexes can form in such extremedilution insofar as interacting groups are concerned, and that they areapparently formed so far removed from their expected stoichiometry(based on small molecule analogs). In the case of acid-base adducts,this invention covers specifically the acid form of sulfonatedterpolymer. These systems contain the low levels of acid groups coupledwith the saturated polymer backbones which combine to make the acid-baseadducts especially preferred.

The amount of vinyl pyridine in the aminecontaining polymer can varywidely, but should range from less than 50 mole percent down to at least0.5 mole percent.

Preferably, the amine content in the basic polymer is expressed in termsof basic nitrogen. In this respect the nitrogen content in amides andsimilar nonbasic nitrogen functionality is not part of the interactingspecies. A minimum of three basic groups must be present on the averageper polymer molecule and the basic nitrogen content generally will rangefrom 4 meq. per 100 grams of polymer up to 500 meq. per 100 grams. Arange of 8 to 200 meq. per 100 grams is preferred.

A means of characterizing the apparent molecular weight of a polymerinvolves the use of melt rheological measurements. For ionic polymersthis is the preferred method since solution techniques are difficult tointerpret due to the complex nature of the ionic associations. Meltrheological measurements of apparent viscosity at a controlledtemperature and shear rate can be used as a measure of apparentmolecular weight of an ionic polymer. Although the exact relationshipbetween melt viscosity and apparent molecular weight for these ionicsystems is not known, for the purposes of this invention therelationship will be assumed to be one of direct proportionality. Thus,in comparing two materials, the one with the higher melt viscosity willbe associated with the higher apparent molecular weight.

The styrene-vinyl pyridine polymers of the polymer complex are formed byfree radical copolymerization using techniques well-known in the polymerliterature. Such polymers can be prepared by a variety of techniqueswith styrene, t-butyl styrene, alkyl acrylates, alkyl methacrylates,butadiene, isoprene vinyl chloride, acrylonitrile,acrylonitrile/butadiene/styrene monomer mixtures and copolymers, or morecomplex mixtures. An emulsion polymerization process is generallypreferred, but other processes are also acceptable.

The polymer complex is formed by either mixing solutions of theindividual polymers or, alternatively, by mixing both polymers in acommon solvent.

The present invention describes a method for reducing the frictionaldrag of an organic liquid in flow through pipes or conduits having acontinuous bore therethrough which comprises adding about 0.001 to about0.5 grams of a polymeric complex to 100 ml of said organic liquid,wherein the polymeric complex is the reaction product of a metalneutralized sulfonated octene-1/ethylene/ethylidene norborene terpolymerand a basic nitrogen-containing copolymer, said basic nitrogencontaining copolymer being a copolymer of vinyl pyridine with anothermonomer selected from the group consisting of styrene, t-butyl styrene,alkylacrylate, alkylmethacrylate, butadiene, isoprene, vinyl chlorideand acrylonitrile

The following Examples illustrate the present invention without,however, limiting the same hereto.

EXAMPLE 1 Preparation of Zinc-Sulfo-Octene-1 Terpolymer

a. Polymerization

A terpolymer of octene-1, ethylene and ENB was prepared in a five liter,well stirred vessel. The charges were: 2,500 ml cyclohexane, 500 mloctene-1, 20 ml ENB and an ethylene feed at a rate of 20 grams per hour.The temperature was kept at 25° C. with nitrogen purge. The catalystcontaining 5.81 grams of VCl₄ and 29.3 grams of ethylene-sesquichloridein a hexane solution was added to the reactor at eight increments of 15minutes apart. The reaction was terminated four hours after theincrement of catalyst addition by precipitation in 3.5 gallons ofisopropanol containing a blend of 30 ml concentrated hydrochloric acidand 70 ml of water. The recovered polymer was purified by redissolvingin hot cyclohexane and precipitation in a blend of acetone-isopropanolcontaining 2 grams of Irganox 1010 antioxidant. The polymer was thenvacuum dried at 70° C., with a final yield of 105 grams. The inherentviscosity in decalin at 135° C. was 0.24.

b. Sulfonation

The polymer of Example 1a was sulfonated using the following procedure:103 grams of polymer was dissolved in 1,169 grams of cyclohexane.Sulfonation was effected by the addition of 20.8 ml of acetyl-sulfate at28° C. After 30 minutes a neutralization agent containing 10.5 grams ofzinc-acetate in 120 ml of methanol was added. The polymer was thenprecipitated in methanol and was vacuum dried at 70° C.

The product contained 15.2 milliequivalents of sulfonate and 0.73 weightpercent of zinc.

EXAMPLE 2 Complex Formation

The sulfonated polymer of Example 1b was dissolved in xylene at aconcentration of one weight percent (Solution A). A second solution wasprepared by dissolving polystyrene-vinylpyridine in xylene at aconcentration of one weight percent (Solution B). The second polymercontained 8 mole percent of pyridine.

The two solutions were mixed at a few ratios to obtain complexes ofzinc-sulfo-octene-1 terpolymers with styrene-vinylpyridine.

The viscosity of various complexes is shown in Table I.

                  TABLE I                                                         ______________________________________                                        Viscosities of Interpolymer Networks                                          in Xylene at 1 Wt. % and 25° C.                                        Composition       Viscosity                                                                              Shear Rate                                         Solution A/Solution B                                                                           cP       1/sec                                              ______________________________________                                        100/0              0.91    300                                                90/10              1,726   1.9                                                80/20             15,340   1.3                                                50/50              1,342   22                                                  0/100            6.0      300                                                ______________________________________                                    

The data in Table I indicate a strong interaction between the polymersin Solutions A and B. The composition of 80/20 shows the highestviscosity is close to the stoichiometric ratio of functional groups inboth polymers.

EXAMPLE 3 Drag Reduction of Improved Interpolymer Complexes

Drag reduction was evaluated by flowing polymer/xylene solutions througha 2.13 mm inside diameter stainless steel tube and measuring theresulting frictional pressure drops and flow rates. The flows weregenerated by loading a pair of stainless steel tanks (1 liter each) witha previously dissolved polymer/xylene solution, pressurizing the tankswith nitrogen gas (300 kPa) and discharging the solution through thetube test section. Pressure drops were measured across by weighingsamples of the effluent liquid collected over measured time periods.

Flow rates in the drag reduction experiments ranged from about 12 to 25g/s; these correspond to solvent Reynolds number from about 12,000 to25,000 (solvent Reynolds number=mean flow velocity times tube diameterdivided by solvent kinematic viscosity). Drag reduction was measured bycomparing flow rates of the polymer/xylene solutions with flow rates ofthe xylene solvent at equal pressure drops of 112 kPa/m. Results wereexpressed as percent flow enhancement, which is defined as: ##EQU1##

Comparisons of two new Zn-S-octene complexes with Zn-S-EPDM complexesare given in Table II. One of the Zn-S-octene polymers (GL-76) isdescribed in Example 1 and Example 2; the other was prepared via similarprocedures. The difference between the polymers is identified in TableII. Also included in the table are baseline data for thestyrene-vinylpyridine copolymer used to form complexes with the othersulfonated polymers; none of the sulfonated polymers show any flowenhancement at 125 ppm concentrations. The data demonstrate thatZn-S-octene complexes produce levels of drag reduction activitycomparable to the Zn-S-EPDM complexes. The data also suggest that lowermolecular weight (inferred from unsulfonated polymer backbone inherentviscosities) sulfonated polymers form more efficient drag reductioncomplexes with this particular styrene-vinylpyridine copolymer.

                  TABLE II                                                        ______________________________________                                        Flow Enhancement Results for                                                  Sulfo-Octene Complexes                                                                              First Pass                                              Polymers              % Flow Enhancement                                      ______________________________________                                        125 ppm SVP           56                                                      (Baseline)                                                                    125 ppm SVP +         76                                                      125 ppm Zn--S--EPDM #1 (GL-75A)                                               125 ppm SVP +         106                                                     125 pm Zn--S--EPDM #2 (GL-88X)                                                125 ppm SVP +         90                                                      125 ppm Zn--S--octene #1 (GL-78)                                              125 ppm SVP +         97                                                      125 ppm Zn--S--octene #2 (GL-76)                                              ______________________________________                                         SVP = styrenevinylpyridine, 8 mole % vinylpyridine, m.w.                      ≈3,000,000;                                                           Zn--S--EPDM #1 = 10 meq SO.sub.3 /100 g polymer with inherent viscosity o     1.5;                                                                          Zn--S--EPDM #2 = 15 meq SO.sub.3 /100 g polymer with inherent viscosity o     ≈0.3;                                                                 Zn--S--octene #1 = 11.2 meq SO.sub.3 /100 g polymer with inherent             viscosity of 0.45;                                                            Zn--S--octene #2 = 15.2 meq SO.sub.3 /100 g polymer with inherent             viscosity of 0.24.                                                       

What is claimed is:
 1. A method for reducing the frictional drag of anorganic liquid in flow through pipes or conduits having a continuousbore therethrough which comprises adding about 0.001 to about 0.5 gramsof a polymeric complex to 100 ml of said organic liquid, wherein thepolymeric complex is the reaction product of a metal neutralizedsulfonated octene-1/ethylene/ethylidene norborene terpolymer and a basicnitrogencontaining copolymer, said basic nitrogen containing copolymerbeing a copolymer of vinylpyridine with another monomer selected fromthe group consisting of styrene, t-butyl styrene, alkylacrylate,alkylmethacrylate, butadiene, isoprene, vinyl chloride andacrylonitrile.
 2. A method according to claim 1 wherein saidstyrene/vinylpyridine copolymer contains about 0.5 to about 50 molepercent of vinylpyridine.
 3. A method according to claim 1 wherein saidsulfonated polymer is in excess of said basic nitrogen containingpolymer.
 4. A method according to claim 1 wherein said basic nitrogencontaining polymer is in excess of said sulfonated terpolymer.